You misunderstand the Bible. No man can serve two masters, for he will hate the one and love the other. No man can serve Scripture and Catholic Tradition.
If by service you mean what I think Jesus meant when he said that, I, as a Catholic convert, don't want to serve either.
Not even if they agree? That makes no sense at all.
By the way, what did all those Christians follow prior to the Gutenberg Bible?
No man should serve either Scripture or Catholic Tradition.
Man should serve God, and only God.
Neither Scripture nor Catholic Tradition is God.
Both are traditions about God.
Both are divinely inspired and protected.
Both serve God.
Men who read Scripture and men who follow the Catholic Tradition carefully are both following that which serves God, and themselves serve God thereby.
It's really not hard. We really are on the same side, you know, with the same Lord, and the same common Enemy. Don't forget that in your zeal to win the intramural soccer match.
When Army plays Navy, West Pointers and Annapolis Midshipmen want to clobber each other's team on the field of play - it is very satisfying. BUT when in the real field of real battle against the real enemy, they are on the same side, and nobody in the Army wants to see the Fleet sunk, and nobody in the Fleet wants to see the Army defeated. A house divided against itself cannot stand, and Catholicism and Protestantism are all pillars of the same Christian house. Your arguments with Catholics should be no different than your arguments with any other sort of Protestant. Presumably you do not think that Presbyterians are evil for following their peculiar Presbyterian traditions, which don't agree with yours. Catholics aren't either. Neither are the Orthodox.
Keep perspective.